The present invention relates generally to notch radiators, and more particularly, to asymmetrically flared notch radiator elements and asymmetrical antenna arrays incorporating such radiator elements for use in phased array antennas.
Conventional flared notch radiators are designed to have a peak antenna gain that lies along an axis normal to the array surface. In addition, specular scattering also occurs at an angle normal to the antenna aperture. Therefore it is impossible to have maximum gain and low radar cross section for a given threat window by simply rotating the array normal to the antenna aperture. It is not possible with a conventional flared notch radiator to have the maximum electric field intensity inside the notch to reside on an axis that is not parallel to the array normal. This property cannot be obtained using the conventional flared notch radiator. Another disadvantage of the conventional flared notch is that its planar geometry does not allow it to be mounted into curved surfaces.
Current and future airborne radars require a reduced radar cross section of its radiating aperture and, in order to detect reduced cross section targets, will require high gain apertures. In low radar cross section applications, conventional radiator elements suffer reduced gain at high angles of incidence, an effect which is compounded for systems using multiple radiators per feed port. Additional losses are encountered due to depolarization losses at high angles of incidence. Thus the competitive advantage of an antenna that does not suffer reduced gain while maintaining a reduced radar signature is very desirable. Future radar application, which envision conformal antenna arrays will need radiators for which the individual element patterns can be aligned in order to achieve good beam formation and low sidelobe control.